Catalyst for catalytic cracking of hydrocarbon, which is used in production of light olefin and production method thereof

ABSTRACT

Disclosed are a molecular sieve catalyst and a preparation method thereof to produce light olefins from cracking naphtha catalytically in severe environments of high temperature and high moisture. In detail, the catalyst is prepared by spray-drying and calcining the mixed slurry, in which 0.01˜5.0 wt % of MnO 2  and 1˜15 wt % of P 2 O 5  are simultaneously imbedded in catalyst which consists of zeolite, clay and inorganic complex. According to the present invention, the method that manganese and phosphate are imbedded simultaneously in zeolite and inorganic complex is used to increases thermal-stability of obtained spherical catalyst, and increase olefin yield of cracking hydrocarbon such as naphtha by protecting acid-site of zeolite. To synthesize the required catalyst, the important procedures are mixing ratio and mixing sequence of Mn, P, zeolite, and inorganic complex.

TECHNICAL FIELD

The present invention relates to a hydrothermally stable porousmolecular sieve catalyst and a preparation method thereof, and moreparticularly to a hydrothermally stable porous molecular sieve catalyst,which, even in an atmosphere of high temperature and humidity, has arelatively stable structure and can maintain its catalytic activity, anda method of preparing the same.

BACKGROUND ART

Porous inorganic materials having a framework of —Si—OH—Al— groups havebeen widely used in the field of porous molecular sieve catalystsbecause they have abundant pores, large specific surface area, and manyactive sites and acid sites.

This porous molecular sieve catalyst is used in, for example,heterogeneous catalytic reactions, such as various oxidation/reductionreactions, including catalytic cracking reactions, isomerizationreactions and esterification reactions, particularly heterogeneouscatalytic reactions requiring thermal stability under a severeatmosphere of high temperature and humidity. In this case, however, thecatalyst has problems in that, when it is placed in a steam atmosphereof more than 500° C., dealumination of its tetrahedral framework willoccur, leading to its structural breakdown, and at the same time, theacid sites of the catalyst will be reduced, resulting in a rapidreduction in catalytic activity. Additionally, since high mechanicalstrength is required for these microporous molecular sieve catalysts inorder to be used in massive fluidized catalytic petrochemical processesfor naphtha catalytic cracking, inorganic complex and matrix(clay) areused for producing spherical catalysts in these area.

Therefore, since microporous molecular sieve catalyst comprising manycomponents such as bonding agent, matrix, and porous molecules,maintaining thermal-stability for the respective component is one of themost important factors to produce proper microporous molecular sievecatalyst. For example, the collapse of matrix structure, which is usedfor microporous molecular sieve catalyst, decreases drastically thereaction rate of naphtha catalytic cracking.

In other hand, in order to achieve high yield of ethylene and propylenein naphtha catalytic cracking process, it is required to control thecharacteristic of acid site in microporous molecular zeolite. If theamount of acid site is large or strength of acidity is strongrelatively, dehydrogenation reaction is faster, and so the yield ofsaturated hydrocarbons such as methane and aromatics such as benzene,toluene and xylene, increases.

On the other hand, if the amount of acid site is small or strength ofacidity is weak relative, conversion of hydrocarbon decreases and solight olefins decrease.

As mentioned above, in order to produce light olefins effectively fromhydrocarbons such as naphtha by catalytic cracking using catalyst, manycharacteristics of catalyst are required. Specially, thethermal-stability is considered to be the most important factor becausethe catalytic cracking catalyst is operated in conditions of hightemperature and high humidity. Many researches have been proposed toincrease thermal-stability.

Regarding these methods, U.S. Pat. No. 5,039,644 discloses a methodusing phosphate in preparing a catalyst which is stable in hightemperature, which comprises 0.5˜15 wt % of P₂O₅ imbedded in porousmetal oxides such as TiO₂, ZrO₂, TiO₂—ZrO₂ mixture, TiO₂—Al₂O₃ mixture,or ZrO₂—Al₂O₃ mixture. However, this patents does not explain how toachieve high yield of light olefins from catalytically crackinghydrocarbons using zeolite.

U.S. Pat. No. 4,977,122 discloses a hydrothermally stable catalyst,which comprises: (a) a crystalline zeolite; (b) an inorganic oxidematrix (e.g., silica, alumina, silica-alumina, magnesia, zirconia,titania, boria, chromia, clay, etc.); and (c) discrete particles ofphosphorus-containing alumina also dispersed in said matrix, saiddiscrete particles having been prepared by contacting alumina with aphosphorus compound selected from the group consisting of an alkalineearth metal salt (Be, Mg, Ca, Sr, Ba) of phosphoric acid or phosphorousacid and mixtures thereof.

U.S. Pat. No. 6,835,863 discloses a process for producing light olefinsby catalytically cracking naphtha (boiling point: 27-221° C.) using apelletized catalyst containing 5-75% by weight of ZSM-5 and/or ZSM-11,25-95% by weight of silica or kaolin and 0.5-10% by weight ofphosphorus. However, there is no mention of the specific phosphorusstarting material or of the hydrothermal stability of the moldedcatalyst.

Meanwhile, U.S. Pat. No. 6,211,104 discloses a catalyst for catalyticcracking, which comprises 10-70 wt % of clay, 5-85 wt % of inorganicoxides and 1-50 wt % of zeolite. The zeolite used in the catalystconsists of 0-25 wt % of Y-zeolite or REY-zeolite and 75-100 wt % ofpentasil zeolite (SiO₂/Al₂O₃=15-60; selected from ZSM-5, ZSM-8 andZSM-11 zeolites containing 2-8 wt % of P₂O₅ and 0.3-3 wt % of Al₂O₃ orMgO or CaO), in which the starting materials of said aluminum ormagnesium or calcium compounds are selected from aqueous solutions oftheir nitrates, hydrochloride, or sulfates. Particularly, the catalystis described as showing excellent olefin production even when pretreatedin an atmosphere of 100% steam at 800° C. for 4-27 hours. However, insaid patent, technology for adjusting/selecting and loading the specificchemical species of P is not disclosed, the added metals are limited toAl, Mg and Ca, and a conventional water-soluble metal salt is used sothat the Al, Mg or Ca cations, which are generated during thepreparation of the catalyst, can be easily ion-exchanged with theprotons of zeolite, resulting in the loss of acidic sites. For thisreason, it is believed that it is not easy to prepare the catalystproposed in said patent under the specified synthesis conditions.

In US publication No. 2005/0020867 A1, the catalyst for light olefinproduction is disclosed, said catalyst is prepared by the stepscomprising that ZSM-5 treated with P₂O₅ 1˜10 wt.% RE2O3 0˜10 wt. %,transition metal (Fe, Co, Ni, Cu, Zn, Mo, Mn) oxides 0.7˜15 wt. % iscompleted by drying and calcination, and then mixed with clay andinorganic bonding agents (silica, alumina, silica-alumina), followed byspray drying. The present ZSM-5 is silica-rich (higher Si/Al ratio) thatmay reduce aromatization and hydrogen transfer reaction. However, thesilica-rich ZSM-5 is not economic for its complicated synthetic method,weak for matrix performance and structural stability by severe thermaltreating with inorganic bonding agents and clay which are not stable athigh temperature steaming. It may cause reducing catalytic crackingactivity of zeolite.

In the U.S. Pat. No. 6,613,710, P-modified clay 40˜80 wt. %, semi-basicalumina 1˜20 wt. %, and ZSM-5 0.5˜15 wt. % are used for the catalyst ofcatalytic cracking reaction. P-modified clay are formed from treatingclay and phosphoric acid at 15˜40° C. for 1˜16 hours, semi-basic aluminafrom slurry of sodium aluminate and aluminum sulfate at pH 7.5˜9. Thepresent catalyst yields more LPG in residual oil cracking within b.p.315˜528° C. This patent is not for host catalyst but for additivecatalyst technology of LPG booster, and there is no disclosure ofhydrothermal stabilization improvement and production of light olefins.

In U.S. Pat. No. 5,670,037, ZSM-5 modified with rare earth metal,calcined by aluminum phosphate sol is proposed for hydrocarbon catalyticcracking to increase light olefin yield. It is prepared by mixing ofP₂O₅ and zeolite (wt. ratio of P₂O₅ to zeolite is 1:5˜99) in aluminumphosphate solution, drying, calcining, and steaming. The completedcatalyst is made of zeolite 10˜35 wt. %, inorganic oxides (Al₂O₃, SiO₂,Al₂O₃—SiO₂) 5˜90 wt. %, and clay 0˜70 wt. %. Aluminum phosphate solutionis used for treating zeolite, and there is no explanation of the yieldincrement of light olefins without the usage of rare earth metal.

In the U.S. Pat. No. 6,080,698, the pentasil-type zeolite catalyst forproduction of light olefin by hydrocarbon catalytic cracking is preparedby ZSM-5 (SiO₂/Al₂O₃=15˜60) treated P₂O₅ 1˜10 wt. %, alkaline earthmetal oxides 0.3˜5 wt. %, and transition metal oxides 0.3˜5 wt. %. Theresults with Mg, Ni, Zn, Cu, and Ca for treatment of zeolite arereported, while the result with manganese oxide is not explained. Thephosphorus is limitedly used to only modify zeolite with transitionmetal.

In the U.S. Pat. No. 6,080,303, the zeolite catalyst for production oflight olefin by hydrocarbon catalytic cracking is prepared by treatingwith aluminum phosphate (AlPO₄). The catalyst is prepared by 1) makingand calcining ZSM-5 with modified with phosphorus, 2) forming AlPO₄ bymixing Al(NO₃)₃ and NH₄(H₂PO₄) at pH 7˜9, 3) treating phosphorus basedZSM-5 with AlPO₄ and calcining. For treatment using AlPO₄, both of driedstate and wet gel state for AlPO₄ may be possible. The completedcatalyst has a composition comprising of P 0.5˜10 wt. %, AlPO₄ 1˜50 wt.%, zeolite 5˜60 wt. %, and balanced binder or clay. In the presentpatent, P and AlPO₄ are used to improve hydrothermal stabilization ofzeolite, and the advantage of the result of hydrothermal treatment ofn-hexane is explained. However, there is no result before hydrothermaltreatment, and no explanation of the stabilization technology of binderand clay as P and AlPO₄ are only used for treating zeolite.

In US Patent 2006/0011513 A1, the catalyst made of ZSM-5, Beta,Mordenite, Ferrierite, and zeolite (silica/alumina>12), which is treatedwith the mixed binder of aluminum phosphate salts and metal phosphatesalts, is proposed as an additive in FCC process. The metal phosphatesalts as binder are selected from IIA group, lanthanoids group, Sc, Y,La, Fe, La, and Ca, and the content of phosphate is more than 5 wt. %,and 4˜50 wt. % is included in typical cases. In this patent, there isnot shown chemical structures of phosphate salts, which is not foractive sites but for binders. Furthermore, there is also not disclosedof improvement of olefin yield by using zeolite formed with manganese.

In the U.S. Pat. No. 5,380,690, catalyst which comprises clay 0˜70%,inorganic oxides such as Al₂O₃, SiO₂, Al₂O₃—SiO₂ 5˜99%, and zeolite1˜50% is disclosed, said catalyst is pentasil zeolite catalyst with Yzeolite 0˜25%, P₂O₅ 75˜100%. ZSM-5. Said catalyst is prepared byuniformly mixing ZSM-5 modified from Re₂O₃ 1˜30% with aluminum phosphatesolution (Al₂O₃:P₂O₅=1:1˜3, wt. ratio, P₂O₅: zeolite=1:5˜99), calcining,and steaming.

In the US patent 2006/0116544, it reports that by treating pentasil typezeolite within rare earth metal and manganese or zirconium withphosphorus, hydrothermal stability and yield of light olefin areimproved. It is required that manganese or zirconium is includedtogether with rare earth metal and phosphorus in zeolite in order toimprove the yield of light olefin. Furthermore, direct injection of rareearth metal and manganese or zirconium and phosphorus in zeolite is usedas treating method. The purpose of this technology is structuralimprovement like the previous ones, and there are no comments aboutstabilization of inorganic binders or matrix contents.

In the U.S. Pat. No. 4,956,075, the Y zeolite catalyst treated withmanganese and rare earth metal is proposed for hydrocarbon catalyticcracking for gasoline with higher octane number. However, the catalysthas less yield of light olefins and hydrothermal stability than pentasiltype catalysts.

Addition of manganese to ZSM-5 may improve hydrothermal stability,reporting in “Studies in Surface Science and Catalysis”, V105,1549(1996). However, there is only explanation of hydrothermalstability, no explanation for production of light olefins by hydrocarboncatalytic cracking.

In the U.S. Pat. No. 6,447,741, aluminophosphate treated by manganese isused for catalyst of catalytic cracking, while there are no results ofsynthesis of catalyst and application for hydrocarbon cracking. Inaddition, in this patent, it is not considered for hydrothermalstability and catalytic characteristics of zeolite, clay and binder.

As explained above, transition metals such as manganese, phosphate andrare earth metals have been proposed to increase thermal-stability ofcatalysts and high yield of light olefins from hydrocarboncatalytic-cracking. However, there is no previous report which explainssystematically how to prepare the catalysts for high thermal-stabilityand high yield of light olefins. That is, there is no previous report asproposed by the present invention, which describes imbedding acid siteof zeolite by manganese, stabilizing inorganic complex and matrix byphosphate and manganese in order to maintain the catalyst activity forlong period and increase yield of light olefins. Also, this presentinvention shows cost-effective procedure for manufacturing catalyst byeliminating complex imbedding step and complex processing sphericalcatalyst.

As described in above comparative patents, phosphate show high abilityto increase thermal-stability of zeolite catalyst. Phosphate increasesthermal-stability by stabilizing Al through acting as phosphate ion([PO₄]³⁻) in —Si—OH—Al— frame which is Bronsted acid site anddealuminated by steam.

However, thermal-stability is affected strongly by how to introducephosphate into zeolite. In order to introduce phosphate into zeolite toincrease thermal-stability, previous methods tried to inject phosphoricacid directly into zeolite. However, large amount of acid sites are lostaccording to these methods. Another method is to use phosphoric acid andrare-earth metals, such as La, together. In this method, large size ofLa³⁺ or phosphoric acid decreases the reaction activity by positioningat entrance of zeolite pore. Additionally since the previous methodstries to make only zeolite itself thermally stable, the problem is thatthe microporous molecular sieve catalyst made by the zeolite does nothave sufficient thermal-stability.

Therefore, the present intention discloses {circle around (1)} a methodto stabilize the catalyst for long period in circumstances of hightemperature and high humidity, {circle around (2)} a method to maximizeyield of light olefins by maintaining acid sites of catalyst afterimbedding.

DISCLOSURE Technical Problem

The present invention provides a cracking catalyst using components tostabilize the inorganic oxide binder and matrix component added toobtain mechanical strength along with maintaining the structure ofzeolite, which is a main catalyst component, under high temperature andhigh humidity for preparing the cracking catalyst withthermal-stability.

An aspect of the present invention provides a method of preparing thecatalyst, which is easy for mass production and economical due to simplesynthesis process, unlike the existing method of preparing the catalyst.

Technical Solution

A hydrocarbon cracking catalyst for preparing light olefin from C4 ormore than C4 hydrocarbon, which is characterized in that 0.01˜5.0 wt %of MnO₂ and 1˜15 wt % of P₂O₅ are simultaneously supported on a catalystcomponent, wherein the catalyst component comprises 1˜50 wt % ofzeolite, 21˜70 wt % of clay, and 1˜40 wt % of an inorganic oxide.

A method of preparing the cracking catalyst for preparing light olefinfrom C4 or more than C4 hydrocarbon, the method comprising the steps of:

(a) Mixing zeolite, clay and inorganic oxide precursor with phosphorusprecursor and manganese precursor with stirring to prepare a mixingslurry; and

(b) spray drying the mixing slurry, followed by calcinations.

Advantageous Effects

The present invention not only improves thermal-stability of thecatalyst by imbedding manganese and phosphorus in the catalystcomprising zeolite, inorganic oxide and clay simultaneously, but alsoobtains high yield of light olefin in catalytically crackinghydrocarbons more than C4 such as naphtha by protecting acid-site ofzeolite. Due to simple method of preparing the catalyst, it is easy andeconomical for mass production.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of manufacturing the catalyst of thispresent invention.

BEST MODE

Compared to the previous inventions, the present intention discloses anew method to achieve simpler catalyst manufacturing, highthermal-stability, and high yield of light olefins in the area ofproducing light olefins from cracking hydrocarbons catalytically.

The method of manufacturing the catalyst of the present inventions isfollowed:

1. For preparing microporous molecular sieve catalyst, the maximalprotection of acid sites of zeolite are accomplished by imbeddingmanganese salt into zeolite in the step of processing slurry ofmicroporous molecular sieve catalyst and by not using the zeolite whichpreviously is imbedded by manganese before slurry processing.

2. In order to increase mechanical strength of microporous molecularsieve catalyst, the present invention stabilizes inorganic complex byinjecting proper amount of phosphorus and manganese contents in the stepof processing slurry of inorganic complex.

3. By mixing zeolite slurry, inorganic complex slurry and clay in final,manganese and phophorus contents could be imbedded in clay, zeolite andinorganic oxide simultaneously so that the stability and activity ofdecomposition is accomplished to be maximized.

As described above, although it is well known that injection ofphosphate or transition metals into zeolite to stabilize the catalyststructure, the present invention firstly disclosed the effective methodto stabilize inorganic complex and clay, and maintain the acid sites ofzeolite maximally by imbedding simultaneously manganese and phosphorusinto zeolite in the step of processing slurry, not in the previous stepsof processing zeolite directly, in order to obtain high yield of lightolefins in catalytically cracking hydrocarbons more than C4.

The catalyst disclosed by the present invention for producing lightolefins from hydrocarbons more than C4 is manufactured by imbeddingsimultaneously 0.01˜5.0 wt % of MnO₂ and 1˜15 wt % of P₂O₅ into catalystcomponents which comprise 1˜50 wt % zeolite, 21˜70 wt % clay, and 1˜40wt % inorganic oxide.

The catalytic cracking catalyst described above is prepared by thefollowing steps: (a) making mixed slurry by mixing phosphate precursorand manganese precursor into zeolite, clay and inorganic oxideprecursor; (b) calcining the above mixed slurry after spray-drying.

In the examples of this present invention, the mixed slurry, in whichphosphate precursor and manganese precursor are mixed into zeolite, clayand inorganic oxide precursor, is prepared, as illustrated in FIG. 1, bysteps comprising (i) manufacturing slurry of zeolite and clay by addingand mixing clay after mixing zeloite and manganese precursor; (ii)manufacturing inorganic oxide slurry by mixing phosphate precursor andmanganese precursor into inorganic oxide precursor; and (iii) mixinguniformly the above zeolite/clay slurry and inorganic oxide slurry.

In another examples prepared by this present invention, the mixedslurry, in which phosphate precursor and manganese precursor are mixedinto zeolite, clay and inorganic oxide precursor, is prepared by stepscomprising (i) manufacturing zeolite slurry by mixing zeolite andmanganese precursor; (ii) manufacturing inorganic oxide slurry by mixingphosphate precursor and manganese precursor into inorganic oxideprecursor; and (iii) mixing uniformly the above zeolite slurry, clayslurry and inorganic oxide slurry.

In another examples prepared by the present invention, the mixed slurry,in which phosphate precursor and manganese precursor are mixed intozeolite, clay and inorganic oxide precursor, is prepared bysimultaneously mixing zeolite, clay inorganic oxide precursor, phosphateprecursor and manganese precursor.

Finally, after spray-drying the above mixed slurry, the catalyst forcatalytic cracking by the present invention is prepared by calcining5˜10 hours in 500˜700° C.

The catalyst prepared by this method has not only improved hydrothermalstability but higher light olefin yield in hydrocarbon catalyticcracking, protecting acid sites in zeolite. Activity cannot beguaranteed if the ratio of each component of manganese, phosphorus,zeolite and inorganic oxides in slurry formation for spray drying andmixing progress are not proper.

Zeolite may be selected from the group consist of ZSM-5 (Si/Al<200, molebase), ZSM-11, Ferrierite, Mordenite, MCM-22, SUZ-4, X-, Y-, andL-Zeolite. Zeolite with Si/Al>200 may reduce activity by little acidsites, and the synthesis for such zeolite is not economical. Followingthe present research, the quantity of zeolite used is 1˜50 wt % based onwhole catalyst weight.

Manganese precursor in this invention could be the one of sulfate,nitrate, chloride, and acetate of manganese, and preferable precursorsare chloride and acetate of manganese.

Improvement of light olefin yield is achieved by protecting acid sitesof zeolite possibly through agitating with manganese precursor in slurrymixture preparation step of zeolite, clay and inorganic oxides, orzeolite slurry preparation step.

It is desirable to use Mn precursor that the MnO₂ is about 0.01˜5.0 wt %based on the final catalyst weight. In case that MnO₂ is less than 0.01wt %, the protection of acid center and hydrothermal stability decrease.In case that MnO₂ is higher than 5.0 wt %, acid center sharply decreasesto lower the activity of catalyst.

For current invention, clay can be used in the range of 21˜70 wt % basedon the final catalyst weight. In case that the amount of clay is lessthan 21 wt %, there are many problems of controlling the physicalproperties such as wear strength and specific gravity. In case that theamount of clay is higher than 70 wt %, catalyst activity could bedecreased.

For the present invention, Al₂O₃, SiO₂ or Al₂O₃—SiO₂ could be used asthe binder of inorganic oxidized precursor. For inorganic oxideprecursor of catalytic cracking catalyst in current invention, inorganicoxide precursor has the form of sol, gel or solution including Al₂O₃,SiO₂, or Al₂O₃—SiO₃. The desirable amount of the inorganic oxide is inthe range of 1˜40 wt % based on the final catalyst. When the amount ofthe inorganic oxide is less than 1 wt %, the wear strength ofmicro-spherical catalyst could be insufficient, whereas in the case thatthe amount of inorganic oxidized substance is higher than 40 wt %, theactivity of catalytic cracking catalyst decreases

For phosphorus precursor of the present invention, it can be used of theaqueous compound which is selected from the group of H₃PO₄, (NH₄)₃PO₄,H(NH₄)₂(PO₄) and H₂(NH₄PO₄), and it is desirable for its contents tohave P₂O₅ content of the final catalyst to be in the range of 1˜15 wt %.In the case that P₂O₅ content of the final catalyst is less than 1 wt %,the hydrothermal stability of zeolite decreases, whereas in the casethat P₂O₅ content of the final catalyst is higher than 15 wt %, theactivity of catalytic cracking decreases due to the excess loss of acidcenter.

Phosphorus and manganese contained in mixed slurry are in the dissolvedform, imbedded to all of zeolite, clay and inorganic oxidized substance.These components protect the acid center of zeolite and increase thehydrothermal stability of zeolite, clay and inorganic oxidized substanceto maximize the stability and activity of catalyst.

Finally, the catalyst for catalytic cracking by current invention isprepared by spary-drying and calcining above mixed slurry at 500˜700° C.for 5˜10 hours.

The prepared catalyst according to the present invention is used asmicrospheroidal molded catalyst for fluidized catalytic processproducing ethylene and propylene from hydrocarbons (carbon number is 4or above) with high yield and high selectivity. Wherein saidhydrocarbons (carbon number is 4 or above) mean hydrocarbons which hasboiling point of 30˜200° C.

Also, even in the condition of high humidity and high temperature, thecatalyst according to the present invention has high cracking activityand stability. Due to this feature, the present catalyst can be used fornot only catalytic cracking reaction but also isomerization reaction,alkylation reaction, esterification reaction and oxidation/reductionreaction which require the high hydrothermal stability.

MODE FOR INVENTION

Hereinafter, the present invention will be described in more detailusing Examples. It is to be understood, however, that these examples arenot to be construed to limit the scope of the present invention

Comparative Example 1 Preparation of P—La—Mn/ZSM-5

40.5 g of MnCl₂.4H₂O was dissolved in 3000 mL of distilled water. To thesolution, 200 g of ZSM-5 was slowly added with stirring for about 3hours at the room temperature. Next, the solution was dried with vacuumdrying, followed by being calcined (650° C., 6 hours). 89 g ofLa(NO₃)₃6H₂O was dissolved in 3000 mL of distilled water, and 200 g ofcalcined sample was added to the solution, followed by stirring 3 hoursat the room temperature. Next the solution was dried with vacuum drying,followed by being calcined (650° C., 6 hours). 25.5 g of 85% H₃PO₄ wasdissolved in 3000 mL of distilled water and 200 g of calcined sample wasadded to the solution, followed by stirring 3 hours at the roomtemperature. Next the solution was dried with vacuum drying, followed bybeing calcined (650° C., 6 hours).

Comparative Example 2 Preparation of P—Mn/ZSM-5

40.5 g of MnCl₂.4H₂O was dissolved in 3000 mL of distilled water, and200 g of ZSM-5 was added to the solution, followed by stirring 3 hoursat the room temperature. Next the solution was dried with vacuum drying,followed by being calcined (650° C., 6 hours). 25.5 g of 85% H₃PO₄ wasdissolved in 3000 mL of distilled water and 200 g of calcined sample wasadded to the solution, followed by stirring 3 hours at the roomtemperature. Next the solution was dried with vacuum drying, followed bybeing calcined (650° C., 6 hours).

Comparative Example 3 Preparation of P/ZSM-5

25.5 g of 85% H₃PO₄ was dissolved in 3000 mL of distilled water and 200g of ZSM-5 was added to the solution, followed by stirring 3 hours atthe room temperature. Next the solution was dried with vacuum drying,followed by being calcined (650° C., 6 hours).

Comparative Example 4˜6

The microsheroidal catalyst for catalytic cracking was prepared withusing the sample of comparative example 4-6, with following procedure.

For preparing the zeolite slurry, 120 g sample of comparative example 1was added to 200 g of distilled water, followed by stirring. Forpreparing the clay slurry, 144 g of clay was added to 176 g of distilledwater, followed by stirring. 439 g of Alumina sol (solid contents 8.4%,pH2˜3) was used for binding zeolite and clay to make the microsheroidalcatalyst. Zeolite slurry, clay slurry and alumina sol were stirredhomogenously, followed by spraying, and drying. Next, thus preparedmaterial was calcined at 650° C. for 6 hours to form the molded catalystof the comparative example 4. With same procedure and method, moldedcatalysts of comparative examples 5 and 6 were prepared using zeolite ofcomparative examples 2 and 3.

Comparative Example 7

For preparing the zeolite slurry, 120 g sample of comparative example 1was slowly added to 200 g of distilled water, followed by stirring. Forpreparing the clay slurry, 144 g of clay was slowly added to 176 g ofdistilled water, followed by stirring. For forming imorgarnic binder tomake the microsheroidal catalyst, 439 g of Alumina sol (solid contents8.4%, pH2˜3) and 33.1 g of 85% H₃PO₄ were homogeneously mixed. Zeoliteslurry, clay slurry and alumina sol-H₃PO₄ mixture were stirredhomogenously, followed by spraying, drying. Next, this was calcined at650° C. for 6 hours, and formed the molded catalyst of the comparativeexample 7.

Chemical compositions of catalyst of comparative example 4-7 aresummarized in the below table 1.

TABLE 1 Comparative Comparative Comparative Comparative Catalyst example4 example 5 example 6 example 7 composition, weight % Zeolite 29.3 33.937.0 27.5 Clay 47.9 47.9 47.9 44.8 Al₂O₃ 12.3 12.3 12.3 11.5 SiO₂ — — —— P₂O₅ 2.9 2.9 2.9 9.1 LaO 5.1 — — 4.7 MnO₂ 2.6 3.0 — 2.5

Example 1-2

4.5 g of MnCl₂.4H₂O was added to 376 mL of distilled water, and 120 g ofZSM-5 was added to this solution, followed by stirring at 60° C. for 6hours. Next, using high viscosity slurry mixer, 144 g of clay was slowlyadded to this solution and stirred for 3 hours. For preparing inorganicbinder, 439 g of alumina sol (solid contents 8.4%, pH2˜3), 30.5 g of 85%H₃PO₄ and 1.8 g of MnCL₂.4H₂O were mixed at 35° C. for 8 hours. Abovezeolite-clay slurry, and inorganic binder were homogeneously mixed,followed by spraying, drying. Next, after being calcined at 650° C. for6 hours, catalyst of example 1 was formed.

The same procedure of example 1 was performed except for the differentamount of samples (11.2 g of MnCl₂.4H₂O was used for ZSM-5 forming, 3.1g of MnCl₂.4H₂O and, 43.8 g of H₃PO₄ was used for inorganic binder) toform the catalyst of example 2.

Example 3-4

4.5 g of MnCl₂.4H₂O was added to 376 mL of distilled water, and 120 g ofZSM-5 was added to this solution, followed by stirring at 60° C. for 6hours. Next, using high viscosity slurry mixer, 144 g of clay was slowlyadded to this solution for 3 hours. 56.7 g of Pseudo Boehmite (Al₂O₃contents 72%) was dispersed in 498 g of distilled water. Next forpreparing inorganic former, this dispersed Pseudo Boehmite solution,30.5 g of 85% H₃PO₄ and 1.8 g of MnCL₂.4H₂O were mixed at 35° C. for 8hours. For preparing the inorganic former, 5.32 g of formic acid wasadded to this mixture and stirred until being stabilized. Abovezeolite-clay slurry, and inorganic binder were homogeneously mixed,followed by spraying, drying. Next, after being calcined at 650° C. for6 hours, catalyst of example 3 was formed.

The same procedure of example 3 was performed except for the differentamount of samples (15.5 g of MnCl₂.4H₂O was used for ZSM-5 forming, 4.8g of MnCl₂.4H₂O and, 51.3 g of H₃PO₄ was used for inorganic binder) toform the catalyst of example 4.

Example 5-6

4.5 g of MnCl₂.4H₂O was added to 376 mL of distilled water, and 120 g ofZSM-5 was added to this solution, followed by stirring at 60° C. for 6hours. Next, using high viscosity slurry mixer, 144 g of clay was slowlyadded to this solution for 3 hours. 23.6 g of water glass (SiO₂ 29%) wasadded to 199 g solution of aluminium sulfate (Al₂O₃ 8%), and mixed. Nextfor preparing inorganic binder, this solution, 15.95 g of 85% H₃PO₄ and1.8 g of MnCL₂.4H₂O were mixed at 35° C. for 8 hours. Above zeolite-clayslurry and inorganic binder were homogeneously mixed, followed byspraying, drying. Next, after being calcined at 650° C. for 6 hours,catalyst of example 5 was formed.

The same procedure of example 5 was performed except for the differentamount of samples (11.4g of MnCl₂.4H₂O was used for ZSM-5 forming, 5.8 gof MnCl₂4H₂O and 71.2 g of H₃PO₄ was used for inorganic former) to formthe catalyst of example 6.

Chemical compositions of catalyst of example 1-6 are summarized in thebelow table 2

TABLE 2 exam- exam- exam- Catalyst ple 1 example 2 example 3 ple 4example 5 ple 6 Composition, weight % Zeolite 37.2 35.9 36.7 34.8 40.235.5 Clay 44.7 43.1 44.1 41.6 48.1 42.6 Al₂O₃ 11.4 11.0 12.5 11.8 5.34.7 SiO₂ — — — — 2.3 2.0 P₂O₅ 5.8 8.1 5.8 9.2 3.3 13.0 LaO — — — — — —MnO₂ 0.9 1.9 0.9 2.6 0.8 2.2

Example 7-8

4.5 g of MnCl₂.4H₂O was added to 376 mL of distilled water, and 90 g ofZSM-5 was added to this solution, followed by stirring at 60° C. for 6hours. Next, using high viscosity slurry mixer, 144 g of clay was slowlyadded to this solution for 3 hours. 62.4 g of Al(NO₃)₃9H₂O was added to220 mL of distilled water, followed that 21.5 g of 85% H₃PO₄ and 1.3 gof MnCl₂.4H₂O were mixed at 35° C. for 8 hours. Above zeolite-clayslurry and this solution were homogeneously mixed, followed by spraying,drying. Next, after being calcined at 650° C. for 6 hours, catalyst ofexample 7 was formed.

The same procedure of example 7 was performed except for the differentamount of samples (120 g of ZSM-5 was used, 11.4 g of MnCl₂.4H₂O wasused for ZSM-5 forming, 5.8 g of MnCl₂.4H₂O and 61.2 g of H₃PO₄ was usedfor inorganic former) to form the catalyst of example 8

Comparative Example 8

120 g of ZSM-5 was stirred with 376 mL of distilled water, at the roomtemperature for 6 hours. Next, using high viscosity slurry mixer, 144 gof clay was slowly added to this solution for 3 hours. 62.4 g ofAl(NO₃)₃9H₂O was added to 220 mL of distilled water, followed by mixingwith 21.5 g of 85% H₃PO₄. Above zeolite-clay slurry and this solutionwere homogeneously mixed, followed by spraying, drying. Next, afterbeing calcined at 650° C. for 6 hours, catalyst of comparative example 8was formed

Comparative Example 9

13.2 g of 85% H₃PO₄ was added to the 576 mL of aqueous solution (22.8 gof MnCl₂.4H₂O and 222.6 g of AlCl₃.6H₂O were dissolved), followed bystirring for 3 hours. This solution was titrated with ammonia water tomake pH=11. After removing the sediment, drying at 100° C., and beingcalcined at 650° C. for 5 hours, MnAlPOx was prepared. 32.6 g of MnAlPOxand 120 g of ZSM-5 were added to 200 g of distilled water, and mixed toform MnAlPOx/ZSM-5 slurry. For preparing the clay slurry, 111.4 g ofclay and 176 g of distilled water were used with above procedure. 439 gof alumina sol (Solid contents 8.4%, pH2˜3), zeolite slurry and clayslurry were homogenously mixed, followed by spraying, drying, and beingcalcined at 650° C. for 6 hours to form the catalyst of comparativeexample 9.

Chemical compositions of catalyst of example 7-8 and comparative example8-9 are summarized in the below table 3

TABLE 3 Comparative Comparative Catalyst example 7 example 8 Example 8Example 9 Composition weight % Zeolite 34.8 37.8 42.0 39.9 Clay 55.845.3 50.4 37.0 Al₂O₃ 3.3 2.7 3.0 20.0 SiO₂ — — — — P₂O₅ 5.1 11.9 4.6 1.4LaO — — — — MnO₂ 1.0 2.38 — 1.7※ Evaluation of Catalyst Activity ※

For evaluation of catalyst activity, 14 catalyst samples of abovecomparative examples 4 to 9 and examples 1 to 8 were steamed at 760□ inan atmosphere of 100% steam for 24 hours. The test conditions forevaluation was that reaction temperature was 675° C., weight hourlyspace velocity (WHSV) was 8/hr, 6 g of catalyst was loaded, and naphtha(Boiling point 30˜135° C.) was used as reactant. Test results aresummarized in Table 4˜6.

From the result, it is obvious that high reaction conversion and highlight olefin yield were obtained by introducing Mn and P to make themicro-spherical catalyst according to the present invention. Mn and Pare effective for stabilizing zeolite, inorganic binder and clay. AlsoMn and P protect the acid center of zeolite to achieve high light olefinyield.

TABLE 4 Comparative Comparative Comparative Comparative ComparativeComparative example 4 example 5 example 6 example 7 example 8 example 9Product distribution, wt % C₂= 16.5 14.4 13.5 13.3 11.2 14.4 C₃= 19.619.4 19.4 19.2 18.1 19.2 C₂− 7.8 7.0 8.5 6.4 5.6 7.5 C₃− 4.9 4.3 6.0 3.22.3 4.1 C₄ 10.6 10.8 10.2 10.1 9.5 10.7 C₅ (iso-C₅, n- 7.4 9.3 10.6 10.612.3 6.8 C₅)

TABLE 5 Example 1 Example 2 Example 3 Example 4 Example 5 Productdistribution, wt % C₂= 19.5 19.4 21.8 21.7 20.5 C₃= 21.4 20.9 20.0 19.821.5 C₂− 9.1 9.6 10.1 10.1 9.1 C₃− 5.8 5.8 4.5 4.3 3.9 C₄ 9.3 9.7 7.47.3 8.4 C₅ (iso-C₅, 4.4 4.2 1.6 1.4 3.6 n-C₅)

TABLE 6 Example 6 Example 7 Example 8 Product distribution, wt % C₂=20.8 21.7 21.9 C₃= 20.3 21.0 22.3 C₂− 9.8 9.5 9.8 C₃− 4.7 3.7 4.1 C₄ 8.57.6 7.0 C₅ (iso-C₅, n-C₅) 2.0 2.4 2.4

As disclosed above, the catalyst according to the present invention ischaracterized in that for achieving high yield of light olefin, zeoliteacid point is treated with Mn, and in order for thus treated zeolite toachieve high activity in the catalyst structure, P and Mn are used tostabilize the inorganic oxide binder and matrix component. The presentmethod for preparing catalyst has advantages from the point of expensecomparing the prior art which generally comprises complicated imbeddingsteps for zeolite.

The invention claimed is:
 1. A method for preparing a catalyst for lightolefins comprising the steps of: (a) mixing ZSM-5 zeolite, clay andinorganic oxide precursor with phosphorus precursor and manganeseprecursor under stirring to prepare a mixing slurry; and (b) spraydrying the mixing slurry, followed by calcinations, to obtain a finalcatalyst wherein the step (a) comprises the steps of: (i) mixing theZSM-5 zeolite with manganese precursor, followed by adding the clay andstirring the mixture to prepare a ZSM-5 zeolite/clay slurry; (ii) mixingthe inorganic precursor with phosphorus precursor and manganeseprecursor under stirring to prepare an inorganic oxide slurry; and (iii)mixing the ZSM-5 zeolite/clay slurry and the inorganic oxide slurryuniformly; wherein both 0.01-5.0 wt % MnO₂ and 1-15 wt % of P₂O₅ areembedded in each of 1-50 wt % of ZSM-5 zeolite, 21-70 wt % of clay, and1-40 wt % of an inorganic oxide in the final catalyst.
 2. A method forpreparing a catalyst for light olefins comprising the steps of: (a)mixing ZSM-5 zeolite, clay and inorganic oxide precursor with phosphorusprecursor and manganese precursor under stirring to prepare a mixingslurry; and (b) spray drying the mixing slurry, followed bycalcinations, wherein the step (a) comprises the steps of: (i) mixingthe ZSM-5 zeolite with manganese precursor to prepare a zeolite slurry;(ii) mixing the inorganic precursor with phosphorus precursor andmanganese precursor under stirring to prepare an inorganic oxide slurry;and (iii) mixing the ZSM-5 zeolite slurry, the inorganic oxide slurry,and clay uniformly; wherein both 0.01-5.0 wt % MnO₂ and 1-15 wt % ofP₂O₅ are embedded in each of 1-50 wt % of ZSM-5 zeolite, 21-70 wt % ofclay, and 1-40 wt % of an inorganic oxide in the final catalyst.
 3. Amethod for preparing a catalyst for light olefins comprising the stepsof: (a) mixing ZSM-5 zeolite, clay and inorganic oxide precursor withphosphorus precursor and manganese precursor under stirring to prepare amixing slurry; and (b) spray drying the mixing slurry, followed bycalcinations to obtain a final catalyst, wherein the step (a) is carriedout by mixing the ZSM-5 zeolite, clay and inorganic oxide precursor,phosphorus precursor and manganese precursor at the same time understirring wherein both 0.01-5.0 wt % MnO₂ and 1-15 wt % of P₂O₅ areembedded in each of 1-50 wt % of ZSM-5 zeolite, 21-70 wt % of clay, and1-40 wt % of an inorganic oxide in the final catalyst.
 4. The method ofclaim 1, wherein the inorganic oxide precursor comprises Al₂O₃, SiO₂ orAl₂O₃—SiO₂, and forms a sol, gel, or solution.
 5. The method of claim 1,wherein the manganese precursor is a sulfate, nitrate, chloride oracetate compound of manganese.
 6. The method of claim 1, wherein thephosphorus precursor is an aqueous phosphorus compound selected from thegroup of H₃PO₄, (NH₄)₃PO₄, H(NH₄)₂(PO₄) and H₂(NH₄)PO₄.
 7. The method ofclaim 2, wherein the inorganic oxide precursor comprises Al₂O₃, SiO₂ orAl₂O₃—SiO₂, and forms a sol, gel, or solution.
 8. The method of claim 3,wherein the inorganic oxide precursor comprises Al₂O₃, SiO₂ orAl₂O₃—SiO₂, and forms a sol, gel, or solution.
 9. The method of claim 2,wherein the manganese precursor is a sulfate, nitrate, chloride oracetate compound of manganese.
 10. The method of claim 3, wherein themanganese precursor is a sulfate, nitrate, chloride or acetate compoundof manganese.
 11. The method of claim 2, wherein the phosphorusprecursor is an aqueous phosphorus compound selected from the group ofH₃PO₄, (NH₄)₃PO₄, H(NH₄)₂(PO₄) and H₂(NH₄)PO₄.
 12. The method of claim3, wherein the phosphorus precursor is an aqueous phosphorus compoundselected from the group of H₃PO₄, (NH₄)₃PO₄, H(NH₄)₂(PO₄) andH₂(NH₄)PO₄.